The Scalability of Trustless Trust

  • Dominik HarzEmail author
  • Magnus Boman
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 10958)


Permission-less blockchains can realise trustless trust, albeit at the cost of limiting the complexity of computation tasks. To explain the implications for scalability, we have implemented a trust model for smart contracts, described as agents in an open multi-agent system. Agent intentions are not necessarily known and autonomous agents have to be able to make decisions under risk. The ramifications of these general conditions for scalability are analysed for Ethereum and then generalised to other current and future platforms. Finally, mechanisms from the trust model are applied to a verifiable computation algorithm and implemented in the Ethereum blockchain. We show in experiments that the algorithm needs at most six semi-honest verifiers to detect false submission.


Trustless trust Smart contract Agent Ethereum Blockchain Scalability Multi-agent system Distributed ledger 



The authors thank Babak Sadighi and Erik Rissanen for comments and discussions, and Daniel Gillblad for important support for Magnus Boman’s part of the project. Also, the authors thank Outlier Ventures Ltd. for partly funding Dominik Harz’ share of the project.


  1. 1.
    Balakrishnan, V., Majd, E.: A comparative analysis of trust models for multi-agent systems. Lect. Notes Softw. Eng. 1(2), 183–185 (2013)Google Scholar
  2. 2.
    Boman, M.: Norms in artificial decision making. Artif. Intell. Law 7(1), 17–35 (1999)Google Scholar
  3. 3.
    Buterin, V.: A Next-Generation Smart Contract and Decentralized Application Platform (2013).
  4. 4.
    Buterin, V.: Chain Interoperability. Technical report 1, R3CEV (2016)Google Scholar
  5. 5.
    Can, A.B., Bhargava, B.: SORT: a self-organizing trust model for peer-to-peer systems. IEEE Trans. Dependable Secure Comput. 10(1), 14–27 (2013)Google Scholar
  6. 6.
    Canetti, R., Riva, B., Rothblum, G.N.: Practical delegation of computation using multiple servers. In: Proceedings of the 18th ACM Conference on Computer and Communications Security - CCS 2011, p. 445. ACM Press, New York (2011)Google Scholar
  7. 7.
    Canetti, R., Riva, B., Rothblum, G.N.: Refereed delegation of computation. Inf. Comput. 226, 16–36 (2013)MathSciNetzbMATHGoogle Scholar
  8. 8.
    Carboni, D.: Feedback based Reputation on top of the Bitcoin Blockchain (2015)Google Scholar
  9. 9.
    Cerutti, F., Toniolo, A., Oren, N., Norman, T.J.: Context-dependent Trust Decisions with Subjective Logic (2013)Google Scholar
  10. 10.
    Decker, C., Wattenhofer, R.: A fast and scalable payment network with bitcoin duplex micropayment channels. In: Pelc, A., Schwarzmann, A.A. (eds.) SSS 2015. LNCS, vol. 9212, pp. 3–18. Springer, Cham (2015). Scholar
  11. 11.
    Ethereum: Ethereum TestRPC (2017).
  12. 12.
    Fishburn, P.: Foundations of decision analysis: along the way. Manag. Sci. 35, 387–405 (1989)MathSciNetzbMATHGoogle Scholar
  13. 13.
    French, S. (ed.): Decision Theory: An Introduction to the Mathematics of Rationality. Halsted Press, New York (1986)zbMATHGoogle Scholar
  14. 14.
    Hoffberg, S.: Multifactorial optimization system and method, 19 April 2007. uS Patent App. 11/467,931
  15. 15.
    Huynh, T.D., Jennings, N.R., Shadbolt, N.R.: An integrated trust and reputation model for open multi-agent systems. Auton. Agents Multi-Agent Syst. 13(2), 119–154 (2006)Google Scholar
  16. 16.
    Jakubowski, M., Venkatesan, R., Yacobi, Y.: Quantifying Trust (2010)Google Scholar
  17. 17.
    Kosba, A., Miller, A., Shi, E., Wen, Z., Papamanthou, C.: Hawk: the Blockchain model of cryptography and privacy-preserving smart contracts. In: 2016 IEEE Symposium on Security and Privacy (SP), vol. 2015, pp. 839–858. IEEE (2016)Google Scholar
  18. 18.
    Litos, O.S.T., Zindros, D.: Trust is risk: a decentralized financial trust platform. IACR Cryptol. ePrint Archive 2017, 156 (2017)Google Scholar
  19. 19.
    Malmnäs, P.E.: Axiomatic justifications of the utility principle. Synthese 99(2), 233–249 (1994)MathSciNetGoogle Scholar
  20. 20.
    Mui, L., Mohtashemi, M., Halberstadt, A.: A computational model of trust and reputation. In: HICSS Proceedings of the 35th Annual Hawaii International Conference on System Sciences, vol. 5, pp. 2431–2439. IEEE (2002)Google Scholar
  21. 21.
    Narayanan, A., Bonneau, J., Felten, E., Miller, A., Goldfeder, S.: Bitcoin and Cryptocurrency Technologies - Draft. Princeton University Press, Princeton (2016)zbMATHGoogle Scholar
  22. 22.
    Odelstad, J., Boman, M.: Algebras for agent norm-regulation. Annals Math. Artif. Intell. 42(1), 141–166 (2004)MathSciNetzbMATHGoogle Scholar
  23. 23.
    Pinyol, I., Sabater-Mir, J.: Computational trust and reputation models for open multi-agent systems: a review. Artif. Intell. Rev. 40(1), 1–25 (2013)Google Scholar
  24. 24.
    Ramchurn, S.D., Huynh, D., Jennings, N.R.: Trust in multi-agent systems. Knowl. Eng. Rev. 19(01), 1–25 (2004)Google Scholar
  25. 25.
    Rasmusson, L., Jansson, S.: Simulated social control for secure Internet commerce. In: Proceedings of the 1996 Workshop on New Security Paradigms - NSPW 1996, pp. 18–25 (1996)Google Scholar
  26. 26.
    Sabater, J., Sierra, C.: Review on computational trust and reputation models. Artif. Intell. Rev. 24(1), 33–60 (2005)zbMATHGoogle Scholar
  27. 27.
    Sandholm, T., Ygge, F.: On the gains and losses of speculation in equilibrium markets. In: Proceedings IJCAI 1997, pp. 632–638. AAAI Press (1997)Google Scholar
  28. 28.
    Szabo, N.: Formalizing and Securing Relationships on Public Networks (1997).
  29. 29.
    Teutsch, J., Reitwießner, C.: A scalable verification solution for blockchains (2017)Google Scholar
  30. 30.
    Vukolić, M.: Hyperledger fabric: towards scalable blockchain for business. Technical report. Trust in Digital Life 2016, IBM Research (2016).
  31. 31.
    Wood, G.: Ethereum: a secure decentralised generalised transaction ledger. Ethereum Project Yellow Paper, pp. 1–32 (2014)Google Scholar
  32. 32.
    Wooldridge, M.: An Introduction to MultiAgent Systems, 2nd edn. Wiley Publishing, Chichester (2009)Google Scholar
  33. 33.
    Zhou, R., Hwang, K., Cai, M.: GossipTrust for fast reputation aggregation in peer-to-peer networks. IEEE Trans. Knowl. Data Eng. 20(9), 1282–1295 (2008)Google Scholar
  34. 34.
    Zyskind, G.: Efficient Secure Computation Enabled by Blockchain Technology. Master thesis, Massachusetts Institute of Technology (2016)Google Scholar

Copyright information

© International Financial Cryptography Association 2019

Authors and Affiliations

  1. 1.IC3RE, Imperial College LondonLondonUK
  2. 2.RISEKistaSweden
  3. 3.KTH/ICT/SCSKistaSweden

Personalised recommendations